Auto merge of #29702 - Loirooriol:outline-offset, r=mrobinson

Implement outline-offset in layout-2020

Tests that are now passing:
- /_mozilla/css/outline_offset_a.htm
- /css/css-ui/outline-010.html
- /css/css-ui/outline-012.html
- /css/css-ui/outline-013.html
- /css/css-ui/outline-017.html
- /css/css-ui/outline-negative-offset-composited-scroll.html
- /css/css-ui/outline-offset-001.html
- /css/css-ui/outline-offset-table-001.html
- /css/css-ui/outline-offset.html
- /css/css-ui/parsing/outline-offset-computed.html
- /css/css-ui/parsing/outline-offset-valid.html

Also improvements in:
- /_mozilla/mozilla/calc.html
- /css/css-ui/animation/outline-offset-interpolation.html
- /css/css-ui/inheritance.html

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- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #29701
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